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POC++ Parameter's Value Changes Between Stack Frames in std::vector
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  1. POC++ Parameter's Value Changes Between Stack Frames in std::vector
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    copied!<p>I've run into a really strange bug, that I'm hoping someone can explain. I have a simple <code>std::vector&lt;V3x&gt;</code>, where <code>V3x</code> is a 3d vector (the linear algebra kind.) The following code causes a <code>std::length_error</code> exception to be thrown:</p> <pre><code>std::vector&lt;V3x&gt; vertices; int vertexCount = computeVertexCount(); vertices.resize(vertexCount); // throws std::length_error </code></pre> <p>I've verified that <code>computeVertexCount()</code> returns a value of <code>35</code>, which is far far below <code>vector::max_size()</code> so there's no way it's asking for too much memory.</p> <p>I traced the exception down into the definition of <code>std::vector</code>, to the following two functions.</p> <pre><code>void resize(size_type _Newsize, _Ty _Val) { // determine new length, padding with _Val elements as needed if (size() &lt; _Newsize) // NOTE: here, _Newsize - size() = 35 _Insert_n(end(), _Newsize - size(), _Val); else if (_Newsize &lt; size()) erase(begin() + _Newsize, end()); } void _Insert_n(const_iterator _Where, size_type _Count, const _Ty&amp; _Val) { // insert _Count * _Val at _Where // NOTE: here, _Count = 3435973836 ... } </code></pre> <p>So when the <code>_Count</code> parameter is passed between <code>resize()</code> and <code>_Insert_n()</code>, the value changes from 35 to 3435973836. I'm assuming the memory has somehow become corrupted, but I have no idea how that could be.</p> <p>For a little more context in case it's part of the problem, this code sits in a .dll plugin that I'm loading from Softimage XSI.</p> <p>Does anyone know what might cause something like this to happen?</p> <p><strong>EDIT: SOLUTION</strong></p> <p>nobugz, I could kiss you.</p> <p>The size of std::vector was changing inside my .dll, because of <code>_HAS_ITERATOR_DEBUGGING</code> in VS2008. The search led me to <a href="http://social.msdn.microsoft.com/Forums/en-US/vcgeneral/thread/efef799e-5d88-4a95-be39-4cd674be5d14/" rel="nofollow noreferrer">someone with the same problem</a>, and it was fixed by adding the following at the top of my project:</p> <pre><code>// fix stack corruption errors caused by VS2008 #define _HAS_ITERATOR_DEBUGGING 0 #define _SECURE_SCL 0 </code></pre>
 

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